Methods, complexes, and system for forming metal-containing films

ABSTRACT

A method of forming a film on a substrate using Group IIIA metal complexes. The complexes and methods are particularly suitable for the preparation of semiconductor structures using chemical vapor deposition techniques and systems.

STATEMENT OF RELATED APPLICATIONS

[0001] The present invention is a Continuation-In-Part of U.S. patentapplication Ser. No. 08/725,064, filed on Oct. 2, 1996, which isincorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to methods and complexes for formingmetal-containing films, such as metal or metal alloy films, particularlyduring the manufacture of semiconductor structures. The complexesinclude a Group IIIA metal, and are particularly suitable for use in achemical vapor deposition system.

BACKGROUND OF THE INVENTION

[0003] Aluminum is one of the three primary materials used today insemiconductor structures, the other two being silicon and silicondioxide. It is primarily used in thin films as an interconnect betweenthe specific structures formed on semiconductor substrates or substrateassemblies. Aluminum has been an important material in the fabricationof semiconductor structures because of its high conductivity, lowresistivity (2.7 μΩ-cm), high adherence to silicon and silicon dioxide,and low stress. Its use is also expanding into other metallizationapplications. For example, it is being examined to replace tungsten incontacts or vias (i.e., very small openings located, for example,between surface conductive paths and or “wiring” and active devices onunderlying layers), which are getting narrower and deeper, and harder tofill with metal.

[0004] Aluminum alloys are also used in semiconductor structures,including alloys of aluminum with copper, titanium, etc., andcombinations thereof. The addition of small quantities (typically, about0.1-4%) of other metals to aluminum improves the electromigrationresistance and reduces the propensity of aluminum thin-films to formhillocks (i.e., protrusions on the aluminum film surface). Such films,however, have increased resistivity over that of pure aluminum films.

[0005] In some applications, aluminum films are deposited usingsputtering techniques; however, sputtered aluminum is not effective atfilling contacts or vias because of shoulders or overhangs that form atthe contact openings. These overhangs can lead to the formation ofkeyhole-shaped voids. Various collimation techniques help reduce thisproblem, but typically not enough to enable complete filling of verysmall geometries (e.g., less than about 0.5 μm). Therefore, it isdesirable to use chemical vapor deposition (CVD) to form aluminum andaluminum alloy films.

[0006] Dimethylaluminum hydride has emerged as one of the preferredmaterials for aluminum metallization by CVD. A serious problem with thismaterial, however, is its pyrophoricity. This problem has been addressedto some degree by the addition of amines to the compound to act asstabilizing Lewis base donors to the aluminum center. However, suchprecursor compounds are still pyrophoric, albeit to a lesser extent. Anadditional complicating factor is introduced into the vapor pressurebehavior of the precursor as a result of dissociation of the amine.Thus, there is a continuing need for methods and precursors for thedeposition of aluminum and aluminum alloy films, as well as other GroupIIIA metal or metal alloy films, on semiconductor structures,particularly using vapor deposition processes.

SUMMARY OF THE INVENTION

[0007] The present invention provides complexes and methods for formingmetal-containing films, particularly Group IIIA metal-containing filmson substrates, such as semiconductor substrates or substrate assemblies,during the manufacture of semiconductor structures. The method involvesforming a metal-containing film using a Group IIIA metal complex,preferably a Group IIIA metal hydride complex. The metal-containing filmcan be used in various metallization layers, particularly in multilevelinterconnects, in an integrated circuit structure.

[0008] The metal-containing film can be a single Group IIIA metal, or ametal alloy containing a mixture of Group IIIA metals or a Group IIIAmetal and one or more metals or metalloids from other groups in thePeriodic Chart, such as copper, silicon, titanium, vanadium, niobium,molybdenum, tungsten, scandium, etc. Furthermore, for certain preferredembodiments, the metal-containing film can be a nitride, phosphide,arsenide, stibnide, or combination thereof. That is, themetal-containing film can be a Group IIIA-VA (e.g., GaAs) semiconductorlayer.

[0009] Thus, in the context of the present invention, the term “GroupIIIA metal-containing film” or simply “metal-containing film” includes,for example, relatively pure films of aluminum, gallium, or indium,alloys of aluminum, gallium, and/or indium with or without othernon-pnicogen metals or metalloids, as well as complexes of these metalsand alloys with Group VA elements (N, P, As, Sb) or mixtures thereof.The terms “single Group IIIA metal film” or “Group IIIA metal film”refer to films of aluminum, gallium, or indium, for example. The terms“Group IIIA metal alloy film” or “metal alloy film” refer to films ofaluminum, gallium, and/or indium alloys with or without other metals ormetalloids, for example. That is, if there are no metals or metalloidsfrom groups in the Periodic Chart other than Group IIIA, the alloy filmscontain combinations of aluminum, gallium, and indium. Preferably, themetal alloy films do not contain Group VA metals or metalloids (i.e.,pnicogens).

[0010] One preferred method of the present invention involves forming afilm on a substrate, such as a semiconductor substrate or substrateassembly during the manufacture of a semiconductor structure, by:providing a substrate (preferably, a semiconductor substrate orsubstrate assembly); providing a precursor comprising one or morecomplexes of the formulas:

[0011] wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ isindependently H or an organic group; x=1 to 3; n=1 to 6 preferably, n=3or 4); y=1 when x=1 and y=3−x when x=2 or 3; and z=3−x−y; and forming ametal-containing film from the precursor on a surface of the substrate(preferably, the semiconductor substrate or substrate assembly). Thedashed arrow indicates that a nitrogen to metal dative bond may or maynot be present. The metal-containing film is a Group IIIA metal film ora Group IIIA metal alloy film. Using such methods, the complexes ofFormulas I and II are converted in some manner (e.g., decomposedthermally) and deposited on a surface to form a Group IIIAmetal-containing film. Thus, the film is not simply a film of thecomplex of Formulas I or II.

[0012] The complexes of Formulas I and II are neutral complexes and maybe liquids or solids at room temperature. If they are solids, they arepreferably sufficiently soluble in an organic solvent to allow forvaporization by flash vaporization, bubbling, microdroplet formation,etc. However, these complexes can also be vaporized or sublimed from thesolid state using known chemical vapor deposition techniques.

[0013] Another method of the present invention involves forming a filmon a substrate, such as a semiconductor substrate or substrate assemblyduring the manufacture of a semiconductor structure, by: providing asubstrate (preferably, a semiconductor substrate or substrate assembly);providing a precursor comprising one or more precursor hydride complexesof Formulas I and II above, wherein: M is a Group IIIA metal; each R¹,R², R³, R⁴, and R⁵ is independently H or an organic group with theproviso that at least one of R³ and R⁴ is H, and R⁵ is H; x=1 to 3; n=1to 6; y=1 when x=1 and y=3−x when x=2 or 3; and z=3−x−y; and forming ametal-containing film from the precursor on a surface of the substrate.

[0014] Yet another method of forming a metal-containing film on asubstrate, such as a semiconductor substrate or substrate assemblyduring the manufacture of a semiconductor structure, by: providing asubstrate (preferably, a semiconductor substrate or substrate assembly);providing a liquid precursor comprising one or more precursor hydridecomplexes of Formulas I and II above, wherein: M is a Group IIIA metal;each R¹, R², R³, R⁴, and R⁵ group is independently H or a(C₁-C₃₀)organic group, with the proviso that at least one of R³ and R⁴is H in Formula I and R⁵ is H in Formula II; x=1 to 3; n=1 to 6; y=1when x=1 and y=3−x when x=2 or 3; and z=3−x−y; vaporizing the liquidprecursor to form vaporized precursor; and directing the vaporizedprecursor toward the substrate to form a metal-containing film on asurface of the substrate.

[0015] Thus, preferred embodiments of the methods of the presentinvention involve the use of one or more chemical vapor depositiontechniques, although this is not necessarily required. That is, forcertain embodiments, sputtering, spin-on coating, etc., can be used.

[0016] The methods of the present invention are particularly well suitedfor forming films on a surface of a semiconductor substrate or substrateassembly, such as a silicon wafer, with or without layers or structuresformed thereon, used in forming integrated circuits. It is to beunderstood that the method of the present invention is not limited todeposition on silicon wafers; rather, other types of wafers (e.g.,gallium arsenide wafer, etc.) can be used as well. Also, the methods ofthe present invention can be used in silicon-on-insulator technology.Furthermore, substrates other than semiconductor substrates or substrateassemblies can be used in the method of the present invention. Theseinclude, for example, fibers, wires, etc. If the substrate is asemiconductor substrate or substrate assembly, the films can be formeddirectly on the lowest semiconductor surface of the substrate, or theycan be formed on any of a variety of the layers (i.e., surfaces) as in apatterned wafer, for example. Thus, the term “semiconductor substrate”refers to the base semiconductor layer, e.g., the lowest layer ofsilicon material in a wafer or a silicon layer deposited on anothermaterial such as silicon on sapphire. The term “semiconductor substrateassembly” refers to the semiconductor substrate having one or morelayers or structures formed thereon. The compounds of Formulas I and IIincorporate features that make them selective for silicon over silicondioxide.

[0017] Also, the present invention provides a hydride complex ofFormulas I or II wherein: M is a Group IIIA metal (preferably Al, Ga,In); each R¹, R², R³, R⁴, and R⁵ group is independently H or an organicgroup, with the proviso that at least one of R³ and R⁴ is H in Formula Iand R⁵ is H in Formula II; x=1 to 3; n=1 to 6; y=1 when x=1 and y=3−xwhen x=2 or 3; and z=3−x−y.

[0018] A chemical vapor deposition system is also provided. The systemincludes a deposition chamber having a substrate positioned therein; avessel containing a precursor comprising one or more complexes ofFormulas I and II wherein M is a Group IIIA metal, each R¹, R², R³, R⁴,and R⁵ group is independently H or an organic group, x=1 to 3, n=1 to 6,y=1 when x=1 and y=3−x when x=2 or 3, and z=3−x−y; and a source of aninert carrier gas for transferring the complexes to the chemical vapordeposition chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional schematic of a semiconductor contactor via having an aluminum film deposited in accordance with the methodof the present invention.

[0020]FIG. 2 is a schematic of a chemical vapor deposition systemsuitable for use in the method of the present invention.

DETAILED DESCRIPTION

[0021] The present invention provides a method of forming a Group IIIAmetal-containing film using one or more Group IIIA metal complexes,preferably a Group IIIA metal hydride complex. These complexes aremononuclear (i.e., monomers in that they contain one metal permolecule). Preferred embodiments display few intermolecular forces ofattraction. Such complexes are generally volatile and transportable inthe gas phase. They preferably have vapor pressures sufficiently lowsuch that they are liquids at room temperature, although they can besolids. If they are solids, they are preferably soluble in organicsolvents, such as aromatic and aliphatic hydrocarbons, nitrites, ethers,amines, etc., which allows for vaporization as a homogeneous mixture bydirect liquid injection. They are also generally compatible with eachother, so that mixtures of variable quantities of the complexes will notinteract to significantly change their physical properties. Preferredembodiments are also generally nonpyrophoric.

[0022] Thus, many of the complexes described herein are suitable for usein chemical vapor deposition (CVD) techniques, such as flashvaporization techniques, bubbler techniques, and the microdroplettechniques. However, these complexes can also be vaporized or sublimedfrom the solid state using other known CVD techniques. Preferredembodiments of the complexes described herein are particularly suitablefor low temperature CVD, i.e., deposition techniques involvingtemperatures of about 50-200° C.

[0023] One preferred method of the present invention involves vaporizinga precursor that includes one or more Group IIIA metal complexes. Forcertain embodiments, the precursor can also include one or more Group VAcomplexes (i.e., a compound containing N, P, As, or Sb). Also, theprecursor can include complexes containing other metals or metalloids(preferably, non-pnicogen metals or metalloids).

[0024] The precursor can be vaporized in the presence of an inertcarrier gas to form a relatively pure metal or metal alloy film. Theinert carrier gas is typically selected from the group consisting ofnitrogen, helium, and argon. In the context of the present invention, aninert carrier gas is one that does not interfere with the formation ofthe metal-containing film. Whether done in the presence of a carrier gasor not, the vaporization is preferably done in the absence of oxygen toavoid oxygen contamination of the films.

[0025] Alternatively, however, the precursor can be vaporized in thepresence of a reaction gas to form a film. The reaction gas can beselected from a wide variety of gases reactive with the complexesdescribed herein, at least at a surface under the conditions of chemicalvapor deposition. Examples of reaction gases include oxygen, nitrousoxide, ammonia, silane, water vapor, hydrogen sulfide, hydrogenselenide, hydrogen telluride, and the like. Various combinations ofcarrier gases and/or reaction gases can be used in the methods of thepresent invention to form metal-containing films.

[0026] The Group IIIA metal complexes described herein are four or fivecoordinate complexes having one or two multidentate ligands, whichtypically have at least one carbon atom that covalently bonds to themetal and one nitrogen atom that forms a dative bond with the metal.None of the complexes herein are written in a manner that specificallyrequires the presence or absence of the nitrogen to metal dative bond.The designation “hydride complex” refers to a Group IIIA metal complexcontaining at least one negatively charged hydride ligand in addition tothe multidentate ligand(s). The multidentate ligand or ligands stabilizethe metal complex by incorporating the nitrogen donor atom into theligand in such a way as to negate dissociation of the ligand prior tothermal decomposition.

[0027] The Group IIIA metal complex is of the following formulas:

[0028] wherein: M is a Group IIIA metal (preferably, Al, Ga, In); each R(i.e., R¹, R², R³, R⁴, and R⁵) is independently H or an organic group(preferably, with the proviso that at least one of R³ and R⁴ is H); x=1to 3; n=1 to 6 (preferably, n=3 or 4); y=1 when x=1 and y=3−x when x=2or 3; and z=3−x−y. More preferably, R² is an organic group, at least oneof R³ and R⁴ is H, and R⁵ is H. The ligand [(C(R¹)₂)_(n)]_(x)N(R²)_(3−x)can bond to the central metal through the nitrogen (although this is notnecessarily required as indicated by the dashed arrow) and at least oneof the C(R¹)₂ units. The R³ and R⁴ groups can be joined to form a ringor rings with the metal, whereas none of the other R groups are joinedtogether to form ring systems. For example, R² does not form a ring withanother R² group or with R¹, R³, R⁴, or R⁵. Also, the R¹ groups are notjoined together to form a ring system.

[0029] A preferred class of complexes of Formulas I and II includehydride complexes wherein: M is a Group IIIA metal (preferably, Al, Ga,In); each R (i.e., R¹, R², R³, R⁴, and R⁵) is independently H or anorganic group, with the proviso that at least one of R³ and R⁴ is H inFormula I and R⁵ is H in Formula II; x=1 to 3; n=1 to 6; y=1 when x=1and y=3−x when x=2 or 3; and z=3−x−y. For these hydride complexes, morepreferably, R² is an organic group. This class of complexes of FormulasI and II (i.e., the hydrides) are particularly advantageous becauseadditional reducing equivalents are present in the complex (as a resultof the hydride ligand(s)), which leads to less carbon contamination ofthe films formed upon decomposition of the complexes.

[0030] As used herein, the term “organic group” means a hydrocarbongroup that is classified as an aliphatic group, cyclic group, orcombination of aliphatic and cyclic groups (e.g., alkaryl and aralkylgroups). The term “aliphatic group” means a saturated or unsaturatedlinear or branched hydrocarbon group. This term is used to encompassalkyl, alkenyl, and alkynyl groups, for example. The term “alkyl group”means a saturated linear or branched hydrocarbon group including, forexample, methyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl,amyl, 2-ethylhexyl, and the like. The term “alkenyl group” means anunsaturated, linear or branched hydrocarbon group with one or morecarbon-carbon double bonds, such as a vinyl group. The term “alkynylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon triple bonds. The term “cyclic group” means aclosed ring hydrocarbon group that is classified as an alicyclic group,aromatic group, or heterocyclic group. The term “alicyclic group” meansa cyclic hydrocarbon group having properties resembling those ofaliphatic groups. The term “aromatic group” or “aryl group” means amono- or polynuclear aromatic hydrocarbon group. The term “heterocyclicgroup” means a closed ring hydrocarbon in which one or more of the atomsin the ring is an element other than carbon (e.g., nitrogen, oxygen,sulfur, etc.).

[0031] In metal complexes such as this, substitution is not onlytolerated, but is often advisable. Thus, substitution is anticipated inthe complexes of the present invention. As a means of simplifying thediscussion and the recitation of certain terminology used throughoutthis application, the terms “group” and “moiety” are used todifferentiate between chemical species that allow for substitution orthat may be substituted and those that do not so allow or may not be sosubstituted. Thus, when the term “group” is used to describe a chemicalsubstituent, the described chemical material includes the unsubstitutedgroup and that group with nonperoxidic O, N, or S atoms, for example, inthe chain as well as carbonyl groups or other conventional substitution.Where the term “moiety” is used to describe a chemical compound orsubstituent, only an unsubstituted chemical material is intended to beincluded. For example, the phrase “alkyl group” is intended to includenot only pure open chain saturated hydrocarbon alkyl substituents, suchas methyl, ethyl, propyl, t-butyl, and the like, but also alkylsubstituents bearing further substituents known in the art, such ashydroxy, alkoxy, alkylsulfonyl, halogen atoms, cyano, nitro, amino,carboxyl, etc. Thus, “alkyl group” includes ether groups, haloalkyls,nitroalkyls, carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On theother hand, the phrase “alkyl moiety” is limited to the inclusion ofonly pure open chain saturated hydrocarbon alkyl substituents, such asmethyl, ethyl, propyl, t-butyl, and the like.

[0032] For the R groups (R¹, R², R³, R⁴, and R⁵) in the complexes ofFormulas I and II, H and (C₁-C₃₀)organic groups are preferred, H and(C₁-C₂₀)organic groups are more preferred, and H and (C₁-C₈)organicgroups are most preferred. Of the organic groups, nonaromatic groups(e.g., aliphatic groups and alicyclic groups, which may or may notinclude unsaturation, and which may or may not include heteroatoms suchas N, O, S, P, Si, etc.) are preferred. Of these, the aliphatic groupsare more preferred, and alkyl moieties (particularly “lower”(C₁-C₄)alkyl moieties). are most preferred. The R³ and R⁴ groups can bejoined to form a ring or rings, whereas none of the other R groups arejoined together to form ring systems.

[0033] Thus, the complexes of Formula I (wherein R¹=H, n=3, x=1, 2, or3, R² is a lower alkyl moiety, and R³ and R⁴ are H or a lower alkylmoiety) can take the following forms (which are representative only):

[0034] The complexes of Formulas I and II are neutral complexes and maybe liquids or solids at room temperature. If they are solids, they arepreferably sufficiently soluble in an organic solvent to allow forvaporization by flash vaporization, bubbling, microdroplet formation,etc. However, these complexes can also be vaporized or sublimed from thesolid state using known chemical vapor deposition techniques.

[0035] Various combinations of the complexes described herein can beused in precursors for chemical vapor deposition. Alternatively, certaincomplexes described herein can be used in other deposition techniques,such as sputtering, spin-on coating, and the like. Typically, thosecomplexes containing R groups with a low number of carbon atoms (e.g.,1-4 carbon atoms per R group) are suitable for use with vapor depositiontechniques. Those complexes containing R groups with a higher number ofcarbon atoms (e.g., 5-12 carbon atoms per R group) are generallysuitable for spin-on or dip coating. Preferably, however, chemical vapordeposition techniques are desired because they are more suitable fordeposition on semiconductor substrates or substrate assemblies,particularly in contact openings which are extremely small and requireconformally filled layers of metal.

[0036] For preparation of films containing Group IIIA-VA (e.g., GaAs)semiconductor materials, the precursors described herein contain one ormore complexes of Formulas I and/or II and an appropriate source of theGroup VA element. Such sources of Group VA elements include compoundssuch as NH₃, PH₃, AsH₃, Me₃As, Me₃Sb, Me₃P, EtAsH₂, Me₂ ^(t)BuSb, etc.

[0037] For the preparation of alloy films, two or more complexes ofFormulas I and/or II can be combined in a precursor mixture (e.g.,AlH₂(CH₂CH₂CH₂NMe₂) and/or AlH(CH₂CH₂CH₂NMe₂)₂ with GaH₂(CH₂CH₂CH₂NMe₂)for an Al—Ga alloy). Alternatively, at least one complex of Formulas Iand/or II can be combined with another complex in a precursor mixture(e.g.,AlH₂(CH₂CH₂CH₂NMe₂) and/or AlH(CH₂CH₂CH₂NMe₂)₂ with Cu(PMe₃)(hfac)for an Al—Cu alloy).

[0038] The complexes of the present invention can be prepared by avariety of methods known to one of skill in the art. For example,AlH₂(CH₂CH₂CH₂NMe₂) and/or AlH(CH₂CH₂CH₂NMe₂)₂ can be prepared byreacting AlCl₃ with ClMg(CH₂)₃NMe₂ followed by reduction.AlH(CH₂CH₂CH₂NMe₂)₂ can be prepared by reacting AlH₃.NEtMe₂ withLiCH₂CH₂CH₂NMe₂ (2 equivalents), followed by distillation of theproduct.

[0039] As stated above, the use of the complexes of Formulas I and/or IIand methods of forming metal-containing films of the present inventionare beneficial for a wide variety of thin film applications insemiconductor structures, particularly various metallization layers. Forexample, such applications include multilevel interconnects in anintegrated circuit structure. Typically, thin films of Group IIIAmetals, such as aluminum, and alloys thereof are deposited aspolycrystalline materials, usually in the 0.5-1.5 μm thickness range.

[0040] A specific example of where a film formed from the complexes ofthe present invention would be useful is the structure shown in FIG. 1.The substrate 16 may be in the form of an n-channel MOSFET (n-channelmetal-oxide semiconductor field-effect transistor), which may be used ina DRAM memory device. As shown, substrate 16 is a p-type silicon havingtwo n-type silicon islands 20 and 22, representing the transistor sourceand drain. Such a construction is well known. The gate for thetransistor is formed by a metal/polysilicon layer 24 deposited over asilicon dioxide layer 26. A relatively thick layer of an insulatingsilicon dioxide 28 overlies the active areas on substrate 16.

[0041] To connect the MOSFET with conductive paths on the surface of thedevice, contacts 30 and 32 have been etched through oxide layer 28 downto the surface of substrate 16. A metal or metal silicide layer 34, suchas titanium silicide, is deposited and formed at the base of contacts 30and 32. A thin, conformal barrier layer of a refractory metal nitride 36(e.g., titanium nitride, titanium aluminum nitride, titanium nitridesilicide) is deposited over the walls of the contacts. Because of thepresence of the conductive barrier layer, the electrical contact path isexcellent and the aluminum metal 38 which is deposited over therefractory metal nitride barrier layer is prevented from attacking thesubstrate surfaces.

[0042] The method of the present invention can be used to deposit ametal-containing film, preferably a metal or metal alloy film, on avariety of substrates, such as a semiconductor wafer (e.g., siliconwafer, gallium arsenide wafer, etc.), glass plate, etc., and on avariety of surfaces of the substrates, whether it be directly on thesubstrate itself or on a layer of material deposited on the substrate asin a semiconductor substrate assembly. The film is deposited uponthermal decomposition of a Group IIIA metal complex that is preferablyeither liquid at the temperature of deposition or soluble in a suitablesolvent that is not detrimental to the substrate, other layers thereon,etc. Preferably, however, solvents are not used; rather, the Group IIIAmetal complexes are liquid and used neat. The method of the presentinvention preferably utilizes vapor deposition techniques, such as flashvaporization, bubbling, etc.

[0043] Conventional bubbler technology can be used to form films fromthe complexes of Formulas I and/or II described above. In conventionalbubbler technology, a carrier gas, typically nitrogen, is bubbledthrough the precursor (which includes either liquid complexes or solidcomplexes dissolved in a liquid medium, such as an organic solvent) tosweep some of the precursor molecules into the processing chamber.

[0044] Alternatives to conventional bubbler technology include anapproach wherein the precursor is heated and vapors are drawn off andcontrolled by a vapor mass flow controller. Further, another way is topump the gas through the precursor using either a very precise meteringpump or a liquid mass flow controller up to the point where it entersthe reaction chamber. At that point, it can either be flash vaporized orinjected directly into a mixing chamber and showerhead where it isvaporized. As described in the article entitled, “Metalorganic ChemicalVapor Deposition By Pulsed Liquid Injection Using An Ultrasonic Nozzle:Titanium Dioxide on Sapphire from Titanium (IV) Isopropoxide,” byVersteeg, et al., i Journal of the American Ceramic Society, 78,2763-2768 (1995) a metalorganic CVD process utilizes pulsed on/offliquid injection in conjunction with atomization by an ultrasonic,piezoelectrically driven nozzle to deliver such metalorganic precursors.The pulse injection is said to allow control of film deposition rates,as fine as monolayers per pulse. The ultrasonic nozzle provides a mistof droplets into the processing chamber of a reactor for reproduciblevaporization of the liquid precursor. Such a delivery system performsthe vaporization in the processing chamber.

[0045] The complexes of Formulas I and II are particularly well suitedfor use with vapor deposition systems, as described in copendingapplication U.S. Ser. No. 08/720,710 entitled “Method and Apparatus forVaporizing Liquid Precursors and System for Using Same,” filed on Oct.2, 1996. Generally, using the method described therein, the vaporizationof a liquid precursor or precursor dissolved in a liquid medium iscarried out in two stages. First, the precursor is atomized or nebulizedgenerating high surface area microdroplets or mist. In the second stage,the constituents of the microdroplets or mist are vaporized by intimatemixture of the heated carrier gas. This two stage vaporization approachprovides a reproducible delivery for precursor complexes (which areeither liquid or solids dissolved in a liquid medium) and providesreasonable growth rates, particularly in device applications with smalldimensions.

[0046] A typical chemical vapor deposition (CVD) system that can be usedto perform the process of the present invention is shown in FIG. 2. Thesystem includes an enclosed chemical vapor deposition chamber 10, whichmay be a cold wall-type CVD reactor. As is conventional, the CVD processmay be carried out at pressures of from atmospheric pressure down toabout 10⁻³ torr, and preferably from about 1.0-0.1 torr. A vacuum may becreated in chamber 10 using turbo pump 12 and backing pump 14.

[0047] One or more substrates 16 (e.g., semiconductor substrates orsubstrate assemblies) are positioned in chamber 10. A constant nominaltemperature is established for the substrate, preferably at atemperature of about 0-600° C., and more preferably at a temperature ofabout 50-300° C. Substrate 16 may be heated, for example, by anelectrical resistance heater 18 on which substrate 16 is mounted. Otherknown methods of heating the substrate may also be utilized.

[0048] In this process, the precursor 40, which contains one or morecomplexes of Formulas I and/or II, is stored in liquid form in vessel42. A source 44 of a suitable inert gas is pumped into vessel 42 andbubbled through the liquid, picking up the precursor and carrying itinto chamber 10 through line 45 and gas distributor 46. Additional inertcarrier gas may be supplied from source 48 as needed to provide thedesired concentration of precursor and regulate the uniformity of thedeposition across the surface of substrate 16. As shown, a series ofvalves 50-54 are opened and closed as required.

[0049] Generally, the precursor is pumped into the CVD chamber 10 at aflow rate of about 1-1000 sccm. The semiconductor substrate is exposedto the precursor at a pressure of about 0.001-100 torr for a time ofabout 0.01-100 minutes. In chamber 10, the precursor will form anadsorbed layer on the surface of substrate 16. As the deposition rate istemperature dependent, increasing the temperature of the substrate willincrease the rate of deposition. Typical deposition rates are about1000-10,000 Å/minute. The carrier gas containing the precursor isterminated by closing valve 53.

[0050] Various combinations of carrier gases and/or reaction gases canbe used in certain methods of the present invention. They can beintroduced into the chemical vapor deposition chamber in a variety ofmanners, such as directly into the vaporization chamber, in combinationwith the precursor, in combination (or in place of) the carrier gas.

[0051] The following examples are offered to further illustrate thevarious specific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention.

EXAMPLES Example 1

[0052] Preparation of AlH₂(CH₂CH₂CH₂NMe₂)

[0053] AlCl₃ (2.0 g, 15 mmol) is added to a dry flask under an inertatmosphere (e.g., argon). To this is added 30 mL of hexanes, and theresulting slurry is cooled to −40° C. A solution of ClMgCH₂CH₂CH₂NMe₂(30 mL of 0.5 M in tetrahydrofuran) is added to the AlCl₃ over 10minutes. The resulting mixture is stirred for 18 hours. The solvent isthen removed in vacuo, resulting in a white solid, which is dried invacuo and then transferred into a sublimator. A white sublimate ofAlCl₂(CH₂CH₂CH₂NMe₂) is obtained at 100° C. and a pressure of 0.5 torr.This product (2.0 g, 10.9 mmol) is dissolved in 30 mL oftetraethyleneglycol dimethylether (i.e., tetraglyme) and added to asuspension of LiAlH₄ (0.82 g, 21.8 mmol) in 20 mL of tetraglyme. Afterstirring for several hours, the product AlH₂(CH₂CH₂CH₂NMe₂) is removedfrom the solvent by vacuum transfer into a liquid nitrogen-cooledreceiver. The resulting colorless product is used for deposition ofAl-containing films.

Example 2

[0054] Preparation of In(CH₃)₂(CH₂CH₂CH₂NMe₂)

[0055] This compound is prepared as described in Hostalek et al., ThinSolid Films, 174, 1 (1989).

Example 3

[0056] Preparation of GaH(CH₃)(CH₂CH₂CH₂NMe₂)

[0057] GaCl₃ (2.0 g, 11.4 mmol) is added to a dry flask under an inertatmosphere (e.g., argon) and suspended in 25 mL of tetrahydrofuran. Tothis suspension is added 22.8 mL (11.4 mmol) of a 0.5 M solution ofClMgCH₂CH₂CH₂NMe₂ in tetrahydrofuran. The mixture is stirred for 18hours. The resulting solution is cooled to −60° C. and then 3.8 mL (11.4mmol) of a 3.0 M solution of MeMgBr in diethyl ether is slowly added.The mixture is allowed to warm to room temperature, and after 2 hoursthe solvent is removed in vacuo. The intermediate,GaCl(CH₃)(CH₂CH₂CH₂NMe₂), is then taken up in 30 mL of tetraglyme andadded dropwise to a suspension of LiAlH₄ (0.43 g, 11.4 mmol) in 20 mL oftetraglyme. After several hours, the product GaH(CH₃)(CH₂CH₂CH₂NMe₂) isremoved from the solvent by vacuum transfer into a liquidnitrogen-cooled receiver. The resulting colorless product is used fordeposition of Ga-containing films.

Example 4

[0058] Preparation of AlH(CH₂CH₂CH₂NMe₂)₂

[0059] A dried flask is charged with AlH₃.NEtMe₂ (6.60 g, 64 mmol) underan inert atmosphere (e.g., argon) and then 50 mL of diethyl ether. Theresulting slurry is cooled to −70° C. and a solution of LiCH₂CH₂CH₂NMe₂(260 mL of 0.5 M solution in diethyl ether) is added. The resultingmixture is allowed to warm slowly to room temperature and stirred for 18hours. The solvent is then removed in vacuo and the crude product istransferred to a smaller distillation apparatus for purification bydistillation under vacuum.

Example 5

[0060] Preparation of Aluminum Thin Films

[0061] A patterned semiconductor wafer is loaded into a CVD chamber, andthe wafer heated to approximately 250° C. The precursor,AlH₂(CH₂CH₂CH₂NMe₂), is loaded into a conventional stainless steelbubbler inside a glove box, and the bubbler transferred to the CVDsystem. A helium carrier gas flow of 50 sccm is established through thebubbler, and a chamber pressure of 0.25 torr is established. Thedeposition is carried out until a desired thickness of aluminum isobtained on the wafer.

[0062] The foregoing detailed description and examples have been givenfor clarity of understanding only. No unnecessary limitations are to beunderstood therefrom. The invention is not limited to the exact detailsshown and described, for variations obvious to one skilled in the artwill be included within the invention defined by the claims. Thecomplete disclosures of all patents, patent documents, and publicationslisted herein are incorporated by reference, as if each wereindividually incorporated by reference.

What is claimed is:
 1. A method of manufacturing a semiconductor structure, the method comprising: providing a semiconductor substrate or substrate assembly; providing a precursor comprising one or more complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein optionally R³ and R⁴ are joined to form a ring or rings with the metal and none of the other R groups are joined together to form ring systems; and n=1 to 6; and forming a metal-containing film from the precursor on a surface of the semiconductor substrate or substrate assembly; wherein the metal-containing film is a Group IIIA metal film or a Group IIIA metal alloy film.
 2. The method of claim 1 wherein the step of forming a metal-containing film comprises vaporizing the precursor to form vaporized precursor and directing the vaporized precursor toward the semiconductor substrate or substrate assembly using a chemical vapor deposition technique.
 3. The method of claim 2 wherein the chemical vapor deposition technique comprises flash vaporization, bubbling, microdroplet formation, or combinations thereof.
 4. The method of claim 1 wherein the semiconductor substrate is a silicon wafer.
 5. The method of claim 1 wherein M is selected from the group consisting of Al, Ga, and In.
 6. The method of claim 1 wherein at least one of R³ and R⁴ is H.
 7. The method of claim 1 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₂₀)organic group.
 8. The method of claim 1 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₄)alkyl moiety.
 9. The method of claim 1 wherein the precursor is a liquid.
 10. The method of claim 9 wherein the liquid precursor comprises one or more solid complexes dissolved in a liquid medium.
 11. A method of manufacturing a semiconductor structure, the method comprising: providing a semiconductor substrate or substrate assembly; providing a precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; forming a metal-containing film from the precursor on a surface of the semiconductor substrate or substrate assembly.
 12. The method of claim 11 wherein the step of forming a metal-containing film comprises vaporizing the precursor to form vaporized precursor and directing the vaporized precursor toward the semiconductor substrate or substrate assembly using a chemical vapor deposition technique.
 13. The method of claim 12 wherein the precursor is vaporized in the presence of a carrier gas.
 14. The method of claim 12 wherein the precursor is vaporized in the presence of a reaction gas.
 15. The method of claim 11 wherein the precursor further comprises one or more compounds containing a Group VA element.
 16. The method of claim 11 wherein the precursor is a liquid.
 17. The method of claim 11 wherein the metal-containing film is a Group IIIA metal film.
 18. The method of claim 11 wherein the metal-containing film is a Group IIIA metal alloy film.
 19. A method of manufacturing a semiconductor structure, the method comprising: providing a semiconductor substrate or substrate assembly; providing a liquid precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀) organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; vaporizing the liquid precursor to form vaporized precursor; and directing the vaporized precursor toward the semiconductor substrate or substrate assembly to form a metal-containing film on a surface of the semiconductor substrate or substrate assembly.
 20. A method of forming a film on a substrate, the method comprising: providing a substrate; providing a precursor comprising one or more complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein optionally R³ and R⁴ are joined to form a ring or rings with the metal and none of the other R groups are joined together to form ring systems; and n=1 to 6; forming a metal-containing film from the precursor on a surface of the substrate; wherein the metal-containing film is a Group IIIA metal film or a Group IIIA metal alloy film.
 21. The method of claim 20 wherein the step of forming a metal-containing film comprises vaporizing the precursor to form vaporized precursor and directing the vaporized precursor toward the substrate using a chemical vapor deposition technique.
 22. The method of claim 20 wherein the precursor is a liquid.
 23. The method of claim 20 wherein the metal-containing film is a Group IIIA metal film.
 24. The method of claim 20 wherein the metal-containing film is a Group IIIA metal alloy film.
 25. The method of claim 20 wherein the step of forming a metal-containing film comprises vaporizing the precursor to form vaporized precursor and directing the vaporized precursor toward the substrate using a chemical vapor deposition technique.
 26. The method of claim 25 wherein the precursor is vaporized in the presence of a carrier gas.
 27. The method of claim 26 wherein the precursor is vaporized in the presence of a reaction gas.
 28. The method of claim 20 wherein the precursor further comprises one or more compounds containing a Group VA element.
 29. The method of claim 23 wherein the precursor is a liquid.
 30. A method of forming a film on a substrate, the method comprising: providing a substrate; providing a precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; forming a metal-containing film from the precursor on a surface of the substrate.
 31. A method of forming a film on a substrate, the method comprising: providing a substrate; providing a liquid precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; vaporizing the liquid precursor to form vaporized precursor; and directing the vaporized precursor toward the substrate to form a metal-containing film on a surface of the substrate.
 32. A hydride complex of the formula:

wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to
 6. 33. The complex of claim 32 wherein M is selected from the group consisting of Al, Ga, and In.
 34. The complex of claim 32 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₂₀)organic group.
 35. The complex of claim 32 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₈)organic group.
 36. The complex of claim 32 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₄)alkyl moiety.
 37. A chemical vapor deposition system comprising: a deposition chamber having a substrate positioned therein; a vessel containing a precursor comprising one or more complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein optionally R³ and R⁴ are joined to form a ring or rings with the metal and none of the other R groups are joined together to form ring systems; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 38. A chemical vapor deposition system comprising: a deposition chamber having a substrate positioned therein; a vessel containing a precursor comprising one or more complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein optionally R³ and R⁴ are joined to form a ring or rings with the metal and none of the other R groups are joined together to form ring systems; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 39. The system of claim 38 wherein M is selected from the group consisting of Al, Ga, and In.
 40. The system of claim 38 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₂₀)organic group.
 41. The system of claim 38 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₈)organic group.
 42. The system of claim 38 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₄)alkyl moiety.
 43. The system of claim 38 wherein the precursor is a liquid.
 44. The system of claim 43 wherein the liquid precursor comprises one or more solid complexes dissolved in a liquid medium.
 45. The system of claim 38 wherein the precursor further comprises one or more compounds containing a Group VA element.
 46. A chemical vapor deposition system comprising: a deposition chamber having a substrate positioned therein; a vessel containing a precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 47. A chemical vapor deposition system comprising: a deposition chamber having a substrate positioned therein; a vessel containing a liquid precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵is H; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 48. A chemical vapor deposition system comprising: a deposition chamber having a semiconductor substrate positioned therein; a vessel containing a precursor comprising one or more complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein optionally R³ and R⁴ are joined to form a ring or rings with the metal and none of the other R groups are joined together to form ring systems; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 49. The system of claim 48 wherein the semiconductor substrate is a silicon wafer.
 50. The system of claim 48 wherein M is selected from the group consisting of Al, Ga, and In.
 51. The system of claim 48 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₂₀)organic group.
 52. The system of claim 48 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₈)organic group.
 53. The system of claim 48 wherein each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₄)alkyl moiety.
 54. The system of claim 48 wherein the precursor is a liquid.
 55. The system of claim 54 wherein the liquid precursor comprises one or more solid complexes dissolved in a liquid medium.
 56. The system of claim 48 wherein the precursor further comprises one or more compounds containing a Group VA element.
 57. A chemical vapor deposition system comprising: a deposition chamber having a semiconductor substrate positioned therein; a vessel containing a precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber.
 58. A chemical vapor deposition system comprising: a deposition chamber having a semiconductor substrate positioned therein; a vessel containing a liquid precursor comprising one or more hydride complexes of the formulas:

 wherein: M is a Group IIIA metal; each R¹, R², R³, R⁴, and R⁵ group is independently H or a (C₁-C₃₀)organic group, wherein none of the R groups are joined together to form ring systems, at least one of R³ and R⁴ is H, and R⁵ is H; and n=1 to 6; and a source of an inert carrier gas for transferring the complex or complexes to the chemical vapor deposition chamber. 